1. Field of the Invention
The present invention relates to a method and apparatus for forming (space) sections, i.e. sections of a continuous slide fastener chain void of interlocking fastener elements, by removing a predetermined number of securely fastened elements from the carrier tapes of the slide fastener chain.
2. Prior Art
To simplify and facilitate the assembling and finishing of slide fasteners, it is common to work on a slide fastener chain or stringer of a continuous length carrying thereon an uninterrupted row or rows of interlocking elements rather than on slide fastener chains or stringers of a definite product length. It is thus customary to provide element-free sections or so-called "space" sections in the chain at predetermined intervals for enabling mounting sliders and end stops, and thereafter to cut the chain or stringer into individual product lengths. The elements to be removed are pressed and deformed at the leg portions thereof followed by abstracting the carrier tapes from the thus deformed elements.
A method for forming space sections according to the above principle is disclosed in Japanese Patent Publication SHO No. 48-32222. The method of this reference comprises pressing and deforming the elements at the leg portions thereof with a punch-die unit and removing the thus deformed elements from the cores of the carrier tapes by merely displacing the portions of the carrier tapes positioned in front of the punch-die unit transversely at substantially a right angle relative to the direction of the element rows. In this type of a method or apparatus therefor, the abstracting angle, i.e. the angle between the row of the elements and the tape core under movement by pulling, differs from element to element being the largest for the element at the most advanced position and smaller for the succeeding elements so that the elements near or at the rear end of the section are removed with difficulty. If the removal conditions are selected to match the elements at the most advanced position, then they are inadequate for the elements at the rear end. If the removal conditions are selected to match the elements at the rearmost position, then there has been needed an excessively strong force resulting in eventual breakage of the carrier tapes.